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Naturalness of the Coleman-Glashow mass relation in the 1/N{sub c} expansion: An update

Description: A new measurement of the {Xi}{sup 0} mass verifies the accuracy of the Coleman-Glashow relation at the level predicted by the 1/N{sub c} expansion. Values for other baryon isospin mass splittings are updated, and continue to agree with the 1/N{sub c} hierarchy.
Date: May 1, 2000
Creator: Jenkins, E. & Lebed, R.F.
Partner: UNT Libraries Government Documents Department

DECAYS OF THE Tz = -2 NUCLEI 20Mg, 24Si AND 36Ca

Description: Beta-delayed protons have been observed from the decays of the mass separated T{sub z} = -2 nuclides {sup 20}Mg, {sup 24}Si, and {sup 36}Ca. From these proton spectra the mass excesses of the lowest T = 2 states in the T{sub z} = -1 nuclei {sup 20}Na, {sup 24}Al, and {sup 36}K are determined to be 13420 {+-} 50 keV ({sup 20}Na), 5903 {+-} 9 keV ({sup 24}Al), and - 13168 {+-} 22 keV ({sup 36}K). The complete A = 20, 24, and 36 isospin quintets have all their members bound against isospin allowed particle-decay modes, providing a stringent test of the isobaric multiplet mass equation. Good agreement is observed for all these quintets using only the quadratic form of this equation. Radioactivity {sup 20}Mg, {sup 24}Si, {sup 36}Ca (mass separated); measured {beta}-delayed protons; deduced T{sub 1/2} and proton branching; derived mass excesses of the lowest 0{sup +}, T = 2 states in {sup 20}Na, {sup 24}Al, and {sup 36}K; deduced coefficients of the isobaric multiplet mass equation.
Date: June 1, 1980
Creator: Aysto, J.; Cable, M.D.; Parry, R.F.; Wouters, J.M.; Moltz, D.M. & Cerny, J.
Partner: UNT Libraries Government Documents Department

Direct CP, Lepton Flavor and Isospin Asymmetries in the Decays B->K(*)l+l-

Description: We measure rate asymmetries for the rare decays B {yields} K{sup (*)}{ell}{sup +}{ell}{sup -}, where {ell}{sup +}{ell}{sup -} is either e{sup +}e{sup -} or {mu}{sup +}{mu}{sup -}, using a sample of 384 million B{bar B} events collected with the BABAR detector at the PEP-II e{sup +}e{sup -} collider. We find no evidence for direct CP or lepton-flavor asymmetries. For dilepton masses below the J/{psi} resonance, we find evidence for unexpectedly large isospin asymmetries in both B {yields} K{ell}{sup +}{ell}{sup -} and B {yields} K*{ell}{sup +}{ell}{sup -} which differ respectively by 3.2{sigma} and 2.7{sigma}, including systematic uncertainties, from the Standard Model expectations.
Date: March 3, 2009
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department

Search for B to rho/omega gamma decays at BaBar

Description: The authors present the results of the search for the decays B{sup 0/{+-}} {yields} {rho}{sup 0/{+-}}{gamma} (previously observed) and B{sup 0} {yields} {omega}{gamma} (for which currently only an upper limit exists). Together with B {yields} K*{gamma} decays, B {yields} ({rho}/{omega}){gamma} allow us to measure the ratio of CKM-matrix elements |V{sub td}/V{sub ts}|. The analysis is based on the full BABAR dataset of 424.35 fb{sup -1} corresponding to 465 million B{bar B} pairs, and makes heavy use of multivariate classification techniques based on decision trees. They find {Beta}(B{sup {+-}} {yields} {rho}{sup {+-}}{gamma}) = (1.20{sub -0.38}{sup +0.42} {+-} 0.20) x 10{sup -6}, {Beta}(B{sup 0} {yields} {rho}{sup 0}{gamma}) = (0.95{sub -0.21}{sup +0.23} {+-} 0.06) x 10{sup -6}, {Beta}(B{sup 0} {yields} {omega}{gamma}) = (0.51{sub -0.24}{sup +0.27} {+-} 0.10) x 10{sup -6}, where the first error is statistical and the second is systematic. They do not observe a statistically significant signal in the latter channel and set an upper limit at {Beta}(B{sup 0} {yields} {omega}{gamma}) < 0.9 x 10{sup -6} (90% C.L.). They also measure the isospin and SU(3){sub F} violating quantities {Lambda}(B{sup +} {yields} {rho}{sup +}{gamma})/2{Lambda}(B{sup 0} {yields} {rho}{sup 0}{gamma})-1 = -0.43{sub -0.22}{sup +0.25} {+-} 0.10 and {Lambda}(B{sup 0} {yields} {omega}{gamma})/{Lambda}(B{sup 0} {yields} {rho}{sup 0}{gamma})-1 = -0.49{sub -0.27}{sup +0.30} {+-} 0.10.
Date: September 23, 2008
Creator: Piatenko, Timofei & /SLAC, /Caltech
Partner: UNT Libraries Government Documents Department

Measurement of alpha / phi_2 from B to pi pi Decays

Description: The current results on B {yields} {pi}{pi} decays and SU(2) constraints on the Unitarity Triangle angle {alpha} or {phi}{sub 2} from the B-factories are summarized. Based on these measurements, predictions of the isospin analysis constraints at the end of the lifetime of both B-factories are given.
Date: January 17, 2007
Creator: Bevan, A.J.
Partner: UNT Libraries Government Documents Department

Measurement of Branching Fractions and CP and Isospin Asymmetry in B->K*(892)gamma Decays

Description: We present an analysis of the decays B{sup 0} {yields} K*{sup 0}(892){gamma} and B{sup +} {yields} K*{sup +}(892){gamma} using a sample of about 383 million B{bar B} events collected with the BABAR detector at the PEP-II asymmetric energy B factory. We measure the branching fractions {Beta}(B{sup 0} {yields} K*{sup 0}{gamma}) = (4.47 {+-} 0.10 {+-} 0.16) x 10{sup -5} and {Beta}(B{sup +} {yields} K*{sup +}{gamma}) = (4.22 {+-} 0.14 {+-} 0.16) x 10{sup -5}. We constrain the direct CP asymmetry to be -0.033 < {Alpha}(B {yields} K*{gamma}) < 0.028 and the isospin asymmetry to be 0.017 < {Delta}{sub 0-} < 0.116, where the limits are determined by the 90% confidence interval and include both the statistical and systematic uncertainties.
Date: June 19, 2009
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department

Top-ophilia

Description: Almost from the moment in June 1977 when the discovery of the Upsilon resonance revealed the existence of what we now call the bottom quark, physicists began searching for its partner. Through the years, as we established the electric charge and weak isospin of the b-quark, and detected the virtual influence of its mate, it became clear that the top quark must exist. Exactly at what mass, we couldn't say, but we knew just how top events would look. We also knew that top events would be rare--if the Tevatron could make them at all--and that picking out the events would pose a real challenge for the experimenters and their detectors.
Date: January 1, 2008
Creator: Quigg, Chris
Partner: UNT Libraries Government Documents Department

B to (rho/omega) gamma at BaBar

Description: This document describes the measurements of the branching fractions and isospin violations of the radiative electroweak penguin decays B {yields} ({rho}/{omega}){gamma} at the asymmetric-energy e{sup +}e{sup -} PEP-II collider with the BABAR detector. Together with the previously measured branching fractions of the decays B {yields} K*{gamma} the ratio of CKM-matrix elements |V{sub td}/V{sub ts}| are extracted and the length of the far side of the unitarity triangle is determined.
Date: February 6, 2008
Creator: Koeneke, Karsten
Partner: UNT Libraries Government Documents Department

The theory of hadronic systems. Annual progress report

Description: This report briefly discusses progress on the following topics: isospin breaking in the pion-nucleon system; the np charge-exchange reaction; energy dependence of pion DCX; pion absorption in nuclei; quantum effects in inclusive reactions; and pion scattering from polarized nuclei.
Date: April 8, 1994
Creator: Gibbs, W.R.
Partner: UNT Libraries Government Documents Department

Tables of SU(3) isoscalar factors

Description: The Clebsch-Gordan coefficients of SU(3) are useful in calculations involving baryons and mesons, as well as in calculations involving arbitrary numbers of quarks. For the latter case, one needs the coupling constants between states of nonintegral hypercharges. The existing published tables are insufficient for many such applications, and therefore we have compiled this collection. This report supplies the isoscalar factors required to reconstruct the Clebsch-Gordan coefficients for a large set of products of representations.
Date: February 16, 1995
Creator: Kaeding, T.A.
Partner: UNT Libraries Government Documents Department

Development of global medium-energy nucleon-nucleus optical model potentials

Description: The authors report on the development of new global optical model potentials for nucleon-nucleus scattering at medium energies. Using both Schroedinger and Dirac scattering formalisms, the goal is to construct a physically realistic optical potential describing nucleon-nucleus elastic scattering observables for a projectile energy range of (perhaps) 20 meV to (perhaps) 2 GeV and a target mass range of 16 to 209, excluding regions of strong nuclear deformation. They use a phenomenological approach guided by conclusions from recent microscopic studies. The experimental database consists largely of proton-nucleus elastic differential cross sections, analyzing powers, spin-rotation functions, and total reaction cross sections, and neutron-nucleus total cross sections. They will use this database in a nonlinear least-squares adjustment of optical model parameters in both relativistic equivalent Schroedinger (including relativistic kinematics) and Dirac (second-order reduction) formalisms. Isospin will be introduced through the standard Lane model and a relativistic generalization of that model.
Date: August 1, 1997
Creator: Madland, D.G. & Sierk, A.J.
Partner: UNT Libraries Government Documents Department

Isospin violation and the proton's neutral weak magnetic form factor

Description: The effects of isospin violation on the neutral weak magnetic form factor of the proton are studied using two-flavour chiral perturbation theory. The first nonzero contributions appear at O(p{sup 4}) in the small-momentum expansion, and the O(p{sup 5}) corrections are also calculated. The leading contributions from an explicit Delta(1232) isomultiplet are included as well. At such a high order in the chiral expansion, one might have expected a large number of unknown parameters to contribute. However, it is found that no unknown parameters can appear within loop diagrams, and a single tree-level counterterm at O(p{sup 4}) is sufficient to absorb all divergences. The momentum dependence of the neutral weak magnetic form factor is not affected by this counterterm.
Date: October 1, 1998
Creator: Lewis, Randy & Mobed, Nader
Partner: UNT Libraries Government Documents Department

Studies of the spin-isospin response of the nuclear continuum using intermediate energy hadrons. Final technical report

Description: The work supported by this grant has had two main thrusts. One involved study of the spin, isospin, and multipole content of the continuum of nuclei, a continuation and completion of work done at LAMPF, Saturne, and TRIUMF. Most of the work has used ({bar p}, {bar p}{prime}) or ({bar d}, {bar d}{prime}) reactions, measuring spin observable to infer properties of the target nuclei. Publications resulting from this work have included seven refereed articles and letters, five abstracts and conference talks, one of which was invited. The second thrust involved preparatory work for experiments at CEBAF. The author was involved in Hall A work and the construction, installation, and initial experiments using the proton focal plane polarimeter. Experiments began in 1997 and no referred publications have yet been completed; ten abstracts and conference talks have been published.
Date: November 1, 1999
Creator: Baker, F.T.
Partner: UNT Libraries Government Documents Department

Studies of nuclear processes at the Triangle Universities Nuclear Laboratory. Final report

Description: The authors concluded their program to establish the trends of isospin mixing in nuclei ranging from {sup 12}C to {sup 40}Ca. This program revealed a systematic variation in the proton reduced widths from one A = 4N nucleus to the next as T = 0 nuclei were bombarded by protons and T = 3/2 states were populated in the compound system. In few-body physics, their program of studies of D-state properties of light nuclei ({sup 3}H, {sup 3}He, and {sup 4}He) resulted in precise determinations of the {eta} parameters for {sup 3}He and {sup 3}H which agreed well with theoretical predictions and served as an important constraint on theoretical calculations. The D{sub 2} parameter determination for {sup 4}He, carried out in collaboration with researchers at Munich and Lisbon, was not as precise but did indicate that {sup 4}He has significant deformation. A program was initiated during this period to measure the ratio of asymptotic D- to S-state normalization constant ({eta}) for {sup 6}Li at Florida State University using the ({sup 6}Li,d) reaction. They determined that the {eta} parameter for {sup 6}Li is extremely small, contrary to expectations.
Date: March 1, 2000
Partner: UNT Libraries Government Documents Department

Neutrons and antimony physical measurements and interpretations

Description: New experimental information for the elastic and inelastic scattering of {approx} 4--10 MeV neutrons from elemental antimony is presented. The differential measurements are made at {approx} 40 or more scattering angles and at incident neutron-energy intervals of {approx} 0.5 MeV. The present experimental results, those previously reported from this laboratory and as found in the literature are comprehensively interpreted using spherical optical-statistical and dispersive-optical models. Direct vibrational processes via core-excitation, isospin and shell effects are discussed. Antimony models for applications are proposed and compared with global, regional, and specific models reported in the literature.
Date: May 23, 2000
Creator: Smith, A. B.
Partner: UNT Libraries Government Documents Department

Structure of neutron-rich nuclei

Description: One of the frontiers of today`s nuclear science is the ``journey to the limits``: of atomic charge and nuclear mass, of neutron-to-proton ratio, and of angular momentum. The new data on exotic nuclei are expected to bring qualitatively new information about the fundamental properties of the nucleonic many-body system, the nature of the nuclear interaction, and nucleonic correlations at various energy-distance scales. In this talk, current developments in nuclear structure of neutron-rich nuclei are discussed from a theoretical perspective.
Date: November 1, 1997
Creator: Nazarewicz, W.
Partner: UNT Libraries Government Documents Department

Expected accuracy in a measurement of the CKM angle alpha using a Dalitz plot analysis of B0 ---> rho pi decays in the BTeV project

Description: A precise measurement of the angle {alpha} in the CKM triangle is very important for a complete test of Standard Model. A theoretically clean method to extract {alpha} is provided by B{sup 0} {yields} {rho}{pi} decays. Monte Carlo simulations to obtain the BTeV reconstruction efficiency and to estimate the signal to background ratio for these decays were performed. Finally the time-dependent Dalitz plot analysis, using the isospin amplitude formalism for tre and penguin contributions, was carried out. It was shown that in one year of data taking BTeV could achieve an accuracy on {alpha} better than 5{sup o}.
Date: December 1, 2005
Creator: Shestermanov, K.E.; Vasiliev, A.N; /Serpukhov, IHEP; Butler, J.; Derevschikov, A.A.; Kasper, P. et al.
Partner: UNT Libraries Government Documents Department

A Precise Sum Rule among Four B -> K pi CP Asymmetries

Description: A sum rule relation is proposed for direct CP asymmetries in B {yields} K{pi} decays. Leading terms are identical in the isospin symmetry limit, while subleading terms are equal in the flavor SU(3) and heavy quark limits. The sum rule predicts A{sub CP}(B{sup 0} {yields} K{sup 0}{pi}{sup 0}) = -0.17 {+-} 0.06 using current asymmetry measurements for the other three B {yields} K{pi} decays. A violation of the sum rule would be evidence for New Physics in b {yields} s{bar q}q transitions.
Date: August 29, 2005
Creator: Gronau, Michael & /Technion, /SLAC
Partner: UNT Libraries Government Documents Department

Measurement of the B to Xs gammaBranching Fraction and Photon Energy Spectrum usingthe Recoil Method

Description: We present a measurement of the branching fraction and photon energy spectrum for the decay B {yields} X{sub s}{gamma} using data from the BABAR experiment. The data sample corresponds to an integrated luminosity of 210 fb{sup -1}, from which approximately 680,000 B{bar B} events are tagged by a fully reconstructed hadronic decay of one of the B mesons. In the decay of the second B meson, an isolated high-energy photon is identified. We measure {Beta}(B {yields} X{sub s}{gamma}) = (3.66 {+-} 0.85{sub stat} {+-} 0.60{sub syst}) x 10{sup -4} for photon energies E{sub {gamma}} above 1.9 GeV in the B rest frame. From the measured spectrum we calculate the first and second moments for different minimum photon energies, which are used to extract the heavy-quark parameters m{sub b} and {mu}{sub {pi}}{sup 2}. In addition, measurements of the direct CP asymmetry and isospin asymmetry are presented.
Date: December 4, 2007
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department

Measurement of the tau- to eta pi-pi+pi-nu tau Branching Fraction and a Search for a Second-Class Current in the tau- to eta'(958)pi-nu tau Decay

Description: The {tau}{sup -} {yields} {eta}{pi}{sup -}{pi}{sup +}{pi}{sup -}{nu}{sub {tau}} decay with the {eta} {yields} {gamma}{gamma} mode is studied using 384 fb{sup -1} of data collected by the BABAR detector. The branching fraction is measured to be (1.60 {+-} 0.05 {+-} 0.11) x 10{sup -4}. It is found that {tau}{sup -} {yields} f{sub 1}(1285){pi}{sup -} {nu}{sub {tau}} {yields} {eta}{pi}{sup -}{pi}{sup +}{pi}{sup -}{nu}{sub {tau}} is the dominant decay mode with a branching fraction of (1.11 {+-} 0.06 {+-} 0.05) x 10{sup -4}. The first error on the branching fractions is statistical and the second systematic. In addition, a 90% confidence level upper limit on the branching fraction of the {tau}{sup -} {yields} {eta}{prime}(958){pi}{sup -}{nu}{sub {tau}} decay is measured to be 7.2 x 10{sup -6}. This last decay proceeds through a second-class current and is expected to be forbidden in the limit of isospin symmetry.
Date: March 24, 2008
Creator: Aubert, B.; Bona, M.; Boutigny, D.; Karyotakis, Y.; Lees, J.P.; Poireau, V. et al.
Partner: UNT Libraries Government Documents Department

The dipion mass spectrum in e+e- annihilation and tau decay: Isospin symmetry breaking effects from the (rho, omega, phi) mixing

Description: A way to explain the puzzling difference between the pion form factor as measured in e{sup +}e{sup -} annihilations and in {tau} decays is discussed. We show that isospin symmetry breaking, beside the already identified effects, produces also a full mixing between the {rho}{sup 0}, {omega} and {phi} mesons which generates an isospin 0 component inside the {rho}{sup 0} meson. This effect, not accounted for in current treatments of the problem, seems able to account for the apparent mismatch between e{sup +}e{sup -} and {tau} data below the {phi} mass.
Date: January 1, 2008
Creator: Benayoun, M.; David, P.; Del Buono, L.; /Paris U., VI-VII; Leitner, O.; /Paris U., VI-VII /Frascati et al.
Partner: UNT Libraries Government Documents Department